(a) Field of the Invention
The present invention relates to a recording medium, in particular relates to an optical information recording medium for use in writing and reading with a high density energy beam such as laser beam.
(b) Description of the Prior Art
A great number of optical information recording mediums for use in writing and reading with a high density energy beam (for instance, such as laser beam) have hitherto been proposed.
As one typical example of such recording mediums there is known an optical information recording medium which comprises a substrate, a metal reflective film and a translucent coloring layer containing a coloring matter. This recording medium is designed so that the laser beam entering the coloring matter-containing translucent coloring layer reaches the metal reflective film and is reflected therefrom so as to detect the reflected beam with ease, wherein said metal reflective film is provided for the purpose of supplementing the deficient amount of the beam reflected from the coloring layer alone. However, the provision of the metal reflective film is defective in that it causes the complicated construction of the information recording medium as well as high costs.
In view of this, it has recently been proposed to eliminate the above mentioned defects by using a high-reflective and bronze-lustered organic coloring matter-containing monolayer film. In particular, when using, as a recording film, a highly light absorptive cyanine coloring matter and making said recording film have a thickness of 300 .ANG. to 600 .ANG., there can be obtained a light absorption reflective film which exhibits metal luster (reflective index: 20 to 30%) and further which permits to effect recording with laser beam and reflective reading with laser beam. In particular, the use of semiconductor laser with wavelength of 750 to 850 nm as the laser source, is advantageous in that a means (an information recording regenerating means which functions to write and read the information by exposing a rotating disk-shaped information recording medium to laser beam radiation) may be minimized.